Covert US strikes against alleged militants in Yemen have risen steeply during the Arab spring, and are currently at the same level as the CIA’s controversial drone campaign in Pakistan, a new study by the Bureau reveals.

At least 27 US military and CIA strikes involving cruise missiles, aircraft, drones or naval bombardments have taken place in the volatile Gulf nation to date, killing hundreds of alleged militants linked to the regional al Qaeda franchise. But at least 55 civilians have died too, the study found.

In the latest attack on March 30, two linked US drone strikes struck a vehicle and house in Azan, Shabwa province. Up to five alleged militants died. But a second vehicle travelling the other way was also struck, killing one civilian and injuring at least five others, according to officials, medics and eyewitnesses.

At least six US attacks --- some involving multiple targets --- have so far taken place in Yemen in March alone, in support of a government offensive to drive militants from key locations. In comparison, Pakistan’s tribal areas, the epicentre of the CIA’s controversial drone war, have seen four US drone strikes in March.

The recent surge in attacks appears linked to the appointment of the new president, Abed Rabbo Mansour Hadi. In his inauguration speech he called for ‘the continuation of war against al-Qaida as a religious and national duty.’

Despite multiple confirmed reports of American military action in Yemen, the US rarely acknowledges its secret war. A State Department spokesperson, speaking on background terms, would this week say only: ‘I refer you to the Government of Yemen for additional information on its counterterrorism efforts.’

Hundreds killed

A detailed examination of US military activity in Yemen over nine years reveals that most attacks – as many as 35 – have taken place after May 2011, as Arab spring-related protests gripped the country.

Total US attacks

27 – 45 (some multiple) with up to 35 since May 2011

Total killed

280 – 522

Civilians reported killed

55-105

All but one of the strikes have taken place under President Obama, who has taken a personal interest in the Yemen campaign. By the time he came to office, Al Qaeda in the Arabian Peninsula (AQAP) had grown to become, in his words, "a network of violence and terror" that had attracted a number of US citizens to its cause, including radical cleric Anwar al-Awlaki.

AQAP even began publishing online propaganda magazines in English, and was behind a number of attempted terrorist attacks against the US, the UK and their allies.

With the CIA heavily engaged in Iraq and Pakistan, the job of crushing AQAP was handed to the Pentagon’s elite Joint Special Operations Command (JSOC) – the same unit that had captured Saddam Hussein and would later kill Osama bin Laden.

But from the start, JSOC’s operations were mired in controversy.

Acting on intelligence that an AQAP meeting was taking place in the southern Yemen desert on December 17 2009, JSOC launched at least one cruise missile loaded with cluster bombs at the gathering. A Yemen parliamentary commission later found that 14 alleged militants died in the attack. But so too did 44 civilians.

A copy of the commission report obtained by the Bureau identifies by name all of the civilians killed, which include five pregnant women and 22 children, the youngest just a year old. Eight families were effectively wiped out, the commission found, although it did not attribute blame to either US or Yemen forces.

Two years on, the US will neither confirm or deny whether any investigation into those deaths has taken place, or if any compensation has been paid to the families of victims. The Pentagon, Centcom, the State Department and US Senate Armed Services Committee all declined to comment on the matter this week.